1. Field of the Invention
The present invention relates to a fuel tank structure for a vehicle having a tank body with a simplified structure, which allows the tank body to be easily fabricated.
2. Description of the Background Art
A vehicular fuel tank structure is known, for example, in Japanese Utility Model Publication No. Hei 5-34265. In FIG. 1 of the above publication, a fuel tank 1 is shown in which an upper fuel supply port 3 is formed in an upper position, a cap 4 is attached to the upper fuel supply port 3, and a fuel pump 7 is disposed in the interior of the fuel tank.
In the above prior art, in addition to the upper fuel supply port 3 for the attachment of the cap 4 thereto, various elements must be formed by molding in the fuel tank 1. These elements include mounting portions for the mounting of tank fittings such as a bracket 6 for fixing the fuel pump 7, a support plate 17 for fixing a fuel pipe 10 and a vent pipe 16, and a residual fuel meter unit for measuring a residual amount of fuel 2. This results in a complicated structure of the fuel tank 1, an increase in the number of machining steps in the manufacture, difficulty of assembly, and an increase of the manufacturing cost.
When forming the fuel tank with a resin by blow molding, the fuel supply port 3 and the bracket 6 are placed into a mold before molding the fuel tank, followed by insert molding. The result is that the fittings mounting work becomes complicated, including positioning of the fuel supply port 3 and the bracket 6. Also, the wall thickness of the insert-molded portion increases, and hence a larger external form of the fuel tank is required for ensuring a predetermined capacity.
It is therefore an object of the present invention to provide a vehicular fuel tank structure having a simple tank body structure, which dispenses with insert molding in the case where the tank body is made of a resin, and which is easily capable of ensuring a predetermined capacity easily and being assembled in an efficient manner.
For achieving the above-mentioned object, a fuel supply port portion of the fuel tank incorporates such tank fittings as a fuel pump and a residual fuel meter unit integrally therein. The fuel supply port portion is formed as a separate member from a tank body of the fuel tank and is removably attached to the tank body. Tank fittings such as a fuel pump and a residual fuel meter unit are integrally incorporated into a fuel supply port portion, and the fuel supply port portion with the tank fittings thus incorporated therein is removably attached to the tank body.
As a result, since the tank body is not required to be formed with tank fittings mounting portions, the structure of the tank body can be simplified, and in the case of forming the tank body with a resin, it is not necessary to perform the insert molding, but a simple blow molding is sufficient, thus permitting the tank body to be fabricated easily. Therefore, the fuel tank manufacturing cost can be reduced. Moreover, since the insert molding is not necessary, it is possible to thin the tank body, which makes it easily possible to ensure a required fuel tank capacity. Further, since tank fittings mounting positions are concentrated in only the fuel supply port portion, it is possible to effect assembly efficiently.
The fuel supply port portion is provided with the fuel pump, a fuel filter housing which receives therein a fuel filter disposed on a discharge side of the fuel pump, and a tank mounting portion for removably mounting the fuel supply port portion to the tank body, in this order. One of a pair of pump shaft support portions for supporting a pump shaft of the fuel pump and one end portion of the fuel filter housing are integrally connected with each other.
One of the pump shaft support portions and the fuel filter housing are sub-assembled and connected integrally. Thereafter, the fuel supply port portion is assembled by the thus sub-assembled pump shaft support portion and fuel filter housing. Since one of the pump shaft support portions and one end portion of the fuel filter housing are integrally connected with each other, it is possible to effect the assembly of the fuel supply port portion easily. Moreover, without separately providing a conduit such as a hose or the like for connecting the fuel pump and the fuel filter housing with each other, a fuel passage can be formed integrally in part of one pump shaft support portion and fuel filter housing, thus making it possible to reduce the number of components used and reduce the number of conduit mounting steps. Further, it is possible to decrease the distance between each pump shaft support portion and the fuel filter housing and hence possible to attain an effective utilization of space and construct the fuel supply port portion compactly in a small size.
A pressure regulator is provided in the fuel supply port portion for regulating the pressure of fuel to be supplied to the engine. An end portion of the pressure regulator and an opposite end portion of the fuel filter housing are integrally connected with each other. The sub-assembled pump shaft support portion and fuel filter housing are further sub-assembled and integrally connected with the pressure regulator. Thereafter, the fuel supply port portion is assembled by the thus sub-assembled pump shaft support portion, fuel filter housing and pressure regulator.
Since the opposite end portion of the fuel filter housing thus sub-assembled with one pump shaft support portion and an end portion of the pressure regulator are integrally connected with each other, the assembly of the fuel supply port portion can be performed more easily. Moreover, a fuel passage can be formed integrally in part of one pump shaft support portion, fuel filter housing and pressure regulator without separately providing conduits such as hoses or the like for connecting the fuel pump, the fuel filter housing, and the pressure regulator with one another. Thus, it is possible to reduce the number of components used and the number of conduit mounting steps. Further, each pump shaft support portion, the fuel filter housing, and the pressure regulator can be disposed at short distances from one another, so that the space concerned can be utilized effectively and the fuel supply port portion can formed compactly in a small size.
A part of a discharge path for discharge of the fuel to the exterior of the fuel tank is integrally formed in the pressure regulator by molding. In comparison with the case where the discharge path is formed separately from the pressure regulator, it is possible to reduce the number of components used and reduce the pressure regulator manufacturing cost and mounting cost.
The tank mounting portion is cylindrical, and a filler serving as a fuel inlet port of the fuel tank is attached to one opening side of the tank mounting portion. A part on an opposite opening side of the tank mounting portion is extended to form an extended portion, and the fuel pump is attached to the extended portion. Since the tank mounting portion is cylindrical, it is easy to mount the filler and it is possible to accommodate tank fittings and form a fuel passage in the interior of the cylinder. Further, since the extended portion is formed, it becomes easier to install the fuel pump and other tank fittings.
A filler serving as a fuel inlet port is provided in the fuel supply port portion, and a filler-side cylindrical portion is provided in the filler. A receiving portion is formed at an opening end of the filler-side cylindrical portion, and the tank body is formed by blow molding. A tank-side cylindrical portion is provided on an opening side of the tank body, and the tank-side cylindrical portion has a protuberance to be disengageably engaged with the receiving portion.
The filler-side cylindrical portion of the filler is fitted on the tank-side cylindrical portion of the tank body and the receiving portion of the filler-side cylindrical portion is brought into engagement with the protuberance of the tank-side cylindrical portion, whereby the filler can be easily coupled to the tank body.
A cylindrical holder is attached to the fuel supply port portion, and the tank fittings are incorporated in the cylindrical holder. A float for detecting a residual fuel quantity is provided in the residual fuel meter unit incorporated in the fuel supply port portion. The float is movable vertically through an arm, and a highest or lowest position in the range of the vertical movement of the float is set within a virtual extended cylinder as an extension of an outer peripheral surface of the cylindrical holder.
Thus, the highest or lowest position in the vertical movement range of the float is set within a virtual extended cylinder as an extension of an outer peripheral surface of the cylindrical holder. In a state in which the float is disposed in the highest or lowest position in its vertical movement range and substantially rectilinearly in the longitudinal direction of the cylindrical holder, the fuel supply port portion is inserted and mounted into the tank body. Thus, when inserting the fuel supply port portion into the tank body, the float is not an obstacle at all and the assembly of the fuel tank can be done smoothly, that is, the productivity of the fuel tank can be improved.
A guide pipe is installed in the fuel supply port portion. The guide pipe conducts the fuel into the tank body during fuel supply and directs a fuel flow in a direction inclined relative to an extending direction of a virtual line which connects an inlet of the fuel supply port portion and the tank fittings, thereby allowing the fuel to flow while avoiding the tank fittings. With the guide pipe provided, the fuel is conducted into the tank body and is allowed to flow while avoiding the tank fittings, thus smoothing the fuel flow and preventing bubbling of the fuel.
A cylindrical holder is attached to the fuel supply port portion, and the tank fittings are incorporated in the cylindrical holder. An outlet of the guide pipe is allowed to face an inner surface of the cylindrical holder located between the fuel supply port portion and the tank fittings. A through hole is formed in a side face portion of the cylindrical holder adjacent to the outlet. In the fuel tank with tank fittings incorporated in the cylindrical holder, a through hole is formed in a side face portion of the cylindrical holder and an outlet of the guide pipe is allowed to face the through hole, allowing the fuel to flow smoothly from the outlet of the guide pipe into the tank body through the through hole formed in the cylindrical holder to prevent bubbling of the fuel.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.